function previewImage(file,imgid,divid)
      {
          var MAXWIDTH  = 100;
          var MAXHEIGHT = 100;
          var div = document.getElementById(divid);
          if (file.files && file.files[0])
          {
              div.innerHTML ='<img id='+imgid+'>';
              var img = document.getElementById(imgid);
              img.onload = function(){
                  var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
                  img.width  =  rect.width;
                  img.height =  rect.height;
//                 img.style.marginLeft = rect.left+'px';
                  img.style.marginTop = rect.top+'px';
              }
              var reader = new FileReader();
              reader.onload = function(evt){img.src = evt.target.result;}
              reader.readAsDataURL(file.files[0]);
          }
          else //兼容IE
          {
              var sFilter='filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale,src="';
              file.select();
              var src = document.selection.createRange().text;
              div.innerHTML = '<img id='+imgid+'>';
              var img = document.getElementById(imgid);
              img.filters.item('DXImageTransform.Microsoft.AlphaImageLoader').src = src;
              var rect = clacImgZoomParam(MAXWIDTH, MAXHEIGHT, img.offsetWidth, img.offsetHeight);
              status =('rect:'+rect.top+','+rect.left+','+rect.width+','+rect.height);
              div.innerHTML = "<div id="+divid+" style='width:"+rect.width+"px;height:"+rect.height+"px;margin-top:"+rect.top+"px;"+sFilter+src+"\"'></div>";
          }
      }
      function clacImgZoomParam( maxWidth, maxHeight, width, height ){
          var param = {top:0, left:0, width:width, height:height};
          if( width>maxWidth || height>maxHeight )
          {
              rateWidth = width / maxWidth;
              rateHeight = height / maxHeight;

              if( rateWidth > rateHeight )
              {
                  param.width =  maxWidth;
                  param.height = Math.round(height / rateWidth);
              }else
              {
                  param.width = Math.round(width / rateHeight);
                  param.height = maxHeight;
              }
          }

          param.left = Math.round((maxWidth - param.width) / 2);
          param.top = Math.round((maxHeight - param.height) / 2);
          return param;
      }